Electronic postage metering systems have been developed which include both a single printing arrangement associated with a single accounting arrangement. These printing and accounting systems have been usually housed in a single secure housing to provide for protection against tampering to provide for security. Other types of electronic postage metering systems have involved the utilization of portable detachably connectable accounting systems such as smart cards and other portable type devices.
These postage meter systems involve both prepayment of postal charges by the mailer (prior to postage value imprinting) and post payment of postal charges by the mailer (subsequent to postage value imprinting). Prepayment meters employ descending registers for securely storing value within the meter prior to printing, while post payment (current account) meters employ ascending registers to account for value imprinted. Postal charges or other terms referring to postal or postage meter or meter system as used herein should be understood to mean charges, meters or systems, for either postal charges, tax charges, private carrier charges, tax service or private carrier service, as the case may be, and other value metering systems, such as certificate metering systems such as is disclosed in U.S. Pat. No. 5,796,841 for SECURE USER CERTIFICATION FOR ELECTRONIC COMMERCE EMPLOYING VALUE METERING SYSTEM, issued Aug. 18, 1998.
Postage metering systems have also been developed which employ encrypted information on a mailpiece. The postage value for a mailpiece may be encrypted together with the other data to generate a digital token. A digital token is encrypted information that authenticates the information imprinted on a mailpiece such as postage value. Examples of postage metering systems which generate and employ digital tokens are described in U.S. Pat. No. 4,757,537 for SYSTEM FOR DETECTING UNACCOUNTED FOR PRINTING IN A VALUE PRINTING SYSTEM, issued Jul. 12, 1988; U.S. Pat. No. 4,831,555 for SECURE POSTAGE APPLYING SYSTEM, issued May 15, 1989; U.S. Pat. No. 4,775,246 for SYSTEM FOR DETECTING UNACCOUNTED FOR PRINTING IN A VALUE PRINTING SYSTEM, issued Oct. 4, 1988; U.S. Pat. No. 4.725,718 for POSTAGE AND MAILING INFORMATION APPLYING SYSTEMS, issued Feb. 16, 1988. These systems, which may utilize a device termed a Postage Evidencing Device (PED) or Postal Security Device (PSD), employ an encryption algorithm which is utilized to encrypt selected information to generate the digital token. The encryption of the information provides security to prevent altering of the printed information in a manner such that any change in a postal revenue block is detectable by appropriate verification procedures.
Encryption systems have also been proposed where accounting for postage payment occurs at a time subsequent to the printing of the postage. Systems of this type are disclosed in U.S. Pat. No. 4,796,193 for POSTAGE PAYMENT SYSTEM FOR ACCOUNTING FOR POSTAGE PAYMENT OCCURS AT A TIME SUBSEQUENT TO THE PRINTING OF THE POSTAGE AND EMPLOYING A VISUAL MARKING IMPRINTED ON THE MAILPIECE TO SHOW THAT ACCOUNTING HAS OCCURRED, issued Jan. 3, 1989; U.S. Pat. No. 5,293,319 for POSTAGE METERING SYSTEM, issued Mar. 8, 1994; and, U.S. Pat. No. 5,375,172, for POSTAGE PAYMENT SYSTEM EMPLOYING ENCRYPTION TECHNIQUES AND ACCOUNTING FOR POSTAGE PAYMENT AT A TIME SUBSEQUENT TO THE PRINTING OF THE POSTAGE, issued Dec. 20, 1994.
Other postage payment systems have been developed not employing encryption. Such a system is described in U.S. Pat. No. 5,319,562 for SYSTEM AND METHOD FOR PURCHASE AND APPLICATION OF POSTAGE USING PERSONAL COMPUTER, issued Feb. 21, 1995. This patent describes a system where end-user computers each include a modem for communicating with a computer and a postal authority. The system is operated under control of a postage meter program which causes communications with the postal authority to purchase postage and updates the contents of the secure non-volatile memory. The postage printing program assigns a unique serial number to every printed envelope and label, where the unique serial number includes a meter identifier unique to that end user. The postage printing program of the user directly controls the printer so as to prevent end users from printing more that one copy of any envelope or label with the same serial number. The patent suggests that by capturing and storing the serial numbers on all mailpieces, and then periodically processing the information, the postal service can detect fraudulent duplication of envelopes or labels. In this system, funds are accounted for by and at the mailer site. The mailer creates and issues the unique serial number which is not submitted to the postal service prior to mail entering the postal service mail processing stream. Moreover, no assistance is provided to enhance the deliverability of the mail beyond current existing systems.
Recently, the United States Postal Service has published proposed draft specifications for future postage payment systems, including the Information Based Indicium Program (IBIP) Indicium Specification dated Jun. 13, 1996; the Information Based Indicia Program Postal Security Device Specification dated Jun. 13, 1996; and, the Host Specification dated Oct. 9, 1996. These are Specifications disclosing various postage payment techniques including various types secure accounting systems that may be employed, as for example, a single chip module, multi chip module, and multi chip stand alone module (See for example, Table 4.6-1 PSD Physical Security Requirements, Page 4-4 of the Information Based Indicia Program Postal Security Device Specification).
In the above identified information based indicium program, the United States Postal Service has specified particular inspection periods which must be implemented for a personal security device or metering type device to remain in service. For such a system to have a high level of security, it is desirable to incorporate a secure clock which is inaccessible by the user so that the unit may not be maintained in operation beyond the inspection expiration date. In systems of this type, the clock may be used to disable operation or disable certain operations of the personal security device. Additionally, another critical function of secure clocks that may be employed in an encrypted indicia type of system is the utilization of the date and time (or portions thereof as part of the encrypted indicia which may be used in verification to insure the validity of the imprint. In such a case, the secure clock, among other functions, provides a changing time which precludes the same personal security device from printing two encrypted indicias having the exact same attributes. This facilitates detection of fraudulent copies of indicias.
Additionally, other enhanced functionalities are obtained by utilization of a secure clock. For example, maintenance cycles can be assured as being initiated within predetermined periods of time since the secure clock may not be altered by the user or service personnel, except under controlled conditions.